Will We Ever see Pneumatic Hybrids?

I have my doubts. The laws of physics have pretty much shown that on every aspect of energy storage in a mobile application electric wins multiple times over any compressed air system.

Size for size a electric system is more efficient and more powerful.

Weight for weight electric is smaller and lighter for the same energy storage capacity.

Efficiency wise electric can run in the high 90% ranges in both power and recharge modes where air compression can't come close.

Mechanical complexity is no match either being electric can reduce the whole system down to one single rotating part and the rest is simple highly reliable electronics and a battery. Compressed air need multistage compressors and pneumatic motors plus heavy tanks and high pressure control valves all with lots of moving parts.

In my opinion its not impossible but for the cost Vs reliability and practicality I don't see how compressed air can ever be an equal match for electric as a short term power storage method on a mobile platform.

Will this thermodynamically bad idea ever go away? This has been beat to death on this forum.

Aside from how wrong it is thermodynamically, you are driving a rolling bomb. The first time a fully charged tank ruptures and takes out a bus full of kids there would be hell to pay.

Yes it is good to recover braking energy, if possible, but it is not the magic answer to the problem.

The best use that this seems to have been put to is for "researchers" to bilk technically un-savy investors out of large sums of money.

So that's why the french compressed air car have not begun mass production...

Vraiment? Tant pis pour eux.

From what I've hear over the years, the French are not renowned for their engineering. Perhaps they should stick with cooking, mmmmm, quite tasty indeed.

Hi Sharkles, The short answer is "NO", it is possible but it is even better using electicity!

Xanasax

<....ever see pneumatic hybrids on the road?....>

Only if each one is towing a Floating Energy Barge.

Oh I missed that one two. I wish these nut job threads would stay in the main section longer or that someone would PM me to know that they are here.

I don't know. I remember reading in popular science years ago about using a simple system in a garbage truck. A garbage truck is a good place to try it because it's big, heavy, doesn't move very fast and stops every 100 meters or less. Pump/compressor technology has practically been around for a couple hundred years and can be made cheap, reliable and light enough for a dump truck. Going through cycles like that would be easy for an air system with technology that's all over the place. But I agree it probably wouldn't work well in a regular car. But for some reason I do remember some article my thermo prof found back in the day about something being feasible that was actually backed up by real math found in every thermo book... but it's been so long I don't recall what it claimed or what the differences were. I remember it making sense at the time (and no it wasn't some miracle solve-all-problems thing, it was just theory). It showed it was possible to make something fairly efficient.

You may be thinking of

http://en.wikipedia.org/wiki/Hydraulic_hybrid

Oh you are right :D http://www.thetruthaboutcars.com/2011/01/chryslers-publicly-funded-hydraulic-hybrid/ It says that the same system is used in trucks :) I was wondering what gas it used, apparently N2. Interesting. It was probably 6 or 7 years ago when I read about this the first time.

I remember when I was with a Company supplying mining equipment that the Americans were producing large bodied vehicles that used a pneumatic/hydraulic system for retrieving and reusing this energy, mainly I think for starting purposes. This was early 1970's